"Ubu Roi" is surely Jarry's most widely known work, and it is an excellent and fun read indeed. However, this edition on New Directions is, unfortunately, badly done.
The translation here is by Barbara Wright, who's translations (of Jarry, Queneau, and others) I generally enjoy. I'm sure this one is equally good, but it is difficult to tell. The entire text of "Ubu Roi" is presented here in hand-written form (scribbled is more like it), with a pen the size of a sharpie. Add to that inane drawings (not Jarry's) around and behind the text on every page. Not only is this very distracting, but some words are not really legible. If you try hard enough you can read it, but it is a very tedious process and completely takes away the fun of reading "Ubu Roi".
With that said, there are a few additional texts in this volume that are printed normally, and which are worthwhile. First is Barbara Wright's useful introduction, and at the end are two essays on the theatre by Jarry, as well as his "Song of Disembraining". The two essays can be found in the Methuen edition, but the "Song..." I have not seen in any other easily available Jarry volume.
I'd highly recommend that any interested reader avoid this edition and pay a few more dollars for the Methuen edition. The translation there (by Connolly and Taylor) is excellent, includes the two subsequent Ubu plays, and features a lengthy introduction and larger selection of Jarry's essays on the theatre.